stupid carbuerator

[v8supergurl]

ive been having a problem with the carbuerators on my 83 kawasaki gpz 750 in fact im not even sure if it is the carbs but lately its been pulling a funny trick on me at about 40kmh the bike suddenly rockets to about 100kmh in an almost uncontrollable manner now at first i was quite sure it was the carbuerators because maybe the carbs were getting stuck and the 4 sliders (the canadian model uses a slider valve as we call it instead of a butterfly one) that let air in werent opening at the same time and so at about 40 my guess was that they probably became unstuck and wacked open all the way causing a sudden burst of speed i checked to see if the carb was working in perfect symphony and it seemed so but still even with the sliders opening at the same time it still pulled the same trick it does the same thing when revving. as soon as it hits 1200rpm it just goes nuts anyone have any idea whats causing this